The present invention relates to a protocol integrating videotex communication system in which data base centers of the CAPTAIN, CEPT, and NAPLPS associated with the videotex presentation level protocol syntax (PLPS) are included in a switching system by use of a gateway apparatus, a videotex communication controller, and an ISDN user/network interface, thereby integrating the service operations.
As the international standards for the videotex PLPS Protocol, there have been recommended three systems including the CAPTAIN, CEPT, and NAPLPS systems; however, the complete interchangability and integration between the different PLPS subscriber's terminals and data base centers remain to be provided.
As a method to solve the problem above, there is known a method described in the Japanese Patent Publication JP-A-62-143586. In this example, as a subscriber's terminal, there is installed a universal terminal having a function of converting a plurality of protocols corresponding to the various PLPS protocols so as to enable videotex communication to be conducted between the single terminal and various kinds of PLPS data base centers. However, since this example requires the conversion functions associated with the respective protocols to be installed in the subscriber's terminal, a problem arises with respect to the cost of the terminal and accommodation thereof.
In addition, Japanese Patent Publication JP-A-62-143586 describes a system in which an identification (ID) transmit function is provided by the subscriber's terminal so that on the data base center side the protocol of the subscriber's terminal is determined depending on the ID, so as to connect the terminal to a communication control unit conforming to the protocol. The system of this configuration is designed to be employed in an environment associated with a telephone network; furthermore, the protocols are limited to the CAPTAIN protocol. Moreover, the object is to access a direct-type information center (DF) for each protocol, which cannot achieve integration of the videotex service.